Researchers from Zhejiang University have developed a highly active, selective, and durable copper nanoparticle catalyst for converting CO₂ to dimethyl ether (DME). This was achieved by loading Cu nanoparticles onto hydrophobic and gallium (Ga)-modified silica supports.

The Ga-modified silica provided moderate acidity for methanol dehydration to DME, which hindered deep dehydration to hydrocarbons. A paper on their work is published in the Chinese Journal of Catalysis.

Optimizing the gallium species and hydrophobic methyl groups on a copper-silica catalyst enhances the conversion of CO2 to DME, accelerating the water removal and improving the catalytic performances. Li et al.

The proximity of Cu and Ga species over the Cu/Ga-SiO₂-20Me catalyst can simultaneously realize the tandem reactions of hydrogenation of CO₂ to methanol and dehydration of methanol to DME, where further transportation and re-adsorption of methanol intermedia to the hydrophobic catalyst was avoided.

The methyl groups efficiently removed the water generated in these two reactions, shifting the reaction equilibrium forward.

Supported Cu catalysts are widely studied for the hydrogenation of CO₂ to dimethyl ether (DME). However, they suffer from insufficient durability and DME selectivity. … we overcome these issues by modulating the gallium species and hydrophobic methyl groups to obtain a silica-supported copper catalyst, achieving a Cu/Ga-SiO₂-Me catalyst with significantly improved DME selectivity and catalyst durability.

—Li et al.

The hydrophobic catalyst surface efficiently hinders the sintering of the Cu nanoparticles, which is usually triggered by water and methanol. Consequently, under the following reaction conditions (6000 mL g_cat^–1·h^–1, 3 MPa, 240 °C), CO₂ conversion of 9.7%, DME and methanol selectivities of 59.3% and 28.4%, and CO selectivity of only 11.3% were obtained. In a continuous evaluation for 100 h, the performance was well maintained without any deactivation trend, outperforming the general supported Cu catalysts.

Resources

• Hangjie Li, Yuehua Xiao, Jiale Xiao, Kai Fan, Bingkuan Li, Xiaolong Li, Liang Wang, Feng-Shou Xiao (2023) “Selective hydrogenation of CO₂ into dimethyl ether over hydrophobic and gallium-modified copper catalysts,” Chinese Journal of Catalysis, Volume 54 doi: 10.1016/S1872-2067(23)64535-8